This invention relates to a system for implanting a prosthesis, and more particularly, to a delivery catheter for placing a graft having an attachment system within a corporeal lumen.
It is well established that various fluid conducting body or corporeal lumens, such as veins and arteries, may deteriorate or suffer trauma so that repair is necessary. For example, various types of aneurysms or other deteriorative diseases may affect the ability of the lumen to conduct fluids and, in turn, may be life-threatening. In some cases, the damaged lumen is repairable only with the use of a prosthesis such as an artificial vessel or graft. For repair of vital vessels such as the aorta, repair may be significantly life-threatening. Techniques known in the art which tend to minimize dangers to the patient include a procedure in which a graft resembling the natural vessel is placed within the diseased or obstructed section of the natural vessel.
More specifically, it is known within the art to provide a prosthesis for intraluminal repair of a vessel. In intraluminal vessel repair, the prosthesis is advanced intraluminally through the vessel to the repair site using a delivery catheter and deployed within the vessel so that the prosthesis traverses the diseased portion to thereby repair the vessel.
Generally speaking, varied concerns arise when repairing the different deteriorated disease that may affect a vessel. For instance, thoracic aneurysms differ from other aortic aneurysms in several respects. As may well be expected, due to their proximity to the heart, there are concerns specific to thoracic aneurysms that are not evident in the repair of other types of aortic aneurysms. Moreover, the size and shape of the thoracic aneurysms differ and are often more varied than other types of aortic aneurysms
In particular, thoracic aneurysms are often close to what are typically called the great arteries, such as the left subclavian artery, or may be found to occur proximal to the celiac trunk. These lumens, which branch away from the thoracic region of the aorta, are critical to the body""s circulatory system and carry high volumes of blood to various parts of the body. Consequently, these lumens generally cannot be occluded by a prosthesis used to intraluminally repair a thoracic aneurysm unless additional procedures are performed to bypass the occluded lumen.
In addition, thoracic aneurysms have diameters that are typically larger and have shapes perhaps more variable than other aortic aneurysms. The average neck diameter of thoracic aneurysms is on the order of 34-36 mm and the average length approximately 10 cm with a range of 5-16 cm. To complicate matters, due to the curvature of the aortic arch, the superior neck of thoracic aneurysms are often at a different angle from that of the inferior neck. Also, among the myriad of shapes they may take on, thoracic aneurysms may be fusiform in shape, or comprise giant penetrating ulcers.
Further, access to thoracic aneurysms through connecting arteries is limited and methods for implanting a prosthesis must take into account the physiology of and effects to the heart. Specifically, the femoral as well as the iliac arteries may be too narrow to pass a catheter for delivering a thoracic prosthesis or graft. Often, surgical repair of a thoracic aortic aneurysm requires thoracotomy. Also, it is not desirable for catheters delivering a thoracic graft to comprise a balloon since the use of the balloon to implant the graft would temporarily stop blood flow, thereby placing potentially dangerous loads upon the heart. Finally, due to high pressures existing in the area of a thoracic aneurysm, the attachment system of a graft for repairing a thoracic aneurysm must be sufficient to prohibit migration of the graft. It is also to be noted that there is typically a lack of calcification in the area of thoracic aneurysms. Consequently, the attachment systems of grafts for repairing thoracic aneurysms generally need not be placed within the lumen with forces overcoming such hardening of tissue.
Thus, what has been needed and heretofore unavailable is a graft and a delivery catheter system therefor, wherein the graft is designed specifically to repair thoracic aortic aneurysms and the delivery system functions to precisely position a graft within an aorta to thereby completely repair the thoracic aneurysm. The graft is to be configured to conform to the various possibilities of shapes of the thoracic aneurysm and to have an attachment system which effectively affixes the graft within the aorta. In addition, the delivery catheter is to effectively operate within the unique anatomical constraints of the thoracic portion of the aorta. The present invention accomplishes these goals.
Briefly, and in general terms, the present invention provides a new and improved graft and delivery catheter and a novel method for their use in repairing a lumen. The graft is configured for repairing a diseased condition of the lumen. The delivery catheter is configured to introduce the graft within or between vessels or corporeal lumens of an animal, such as a human, and to facilitate the deployment of the graft at the repair sites.
The present graft has a diameter that is larger than that of conventional grafts so that relatively larger lumens may be repaired and its walls are thinner to facilitate packing it within the delivery catheter. The attachment system of the present graft is expandable and is stiffer and has hooks with greater angles from radial than conventional attachment systems. Also, in addition to being secured to the ends of the graft, the attachment system is secured by its apices to the graft to prevent relative motion of the attachment system and graft. Further, the novel attachment system of the present graft enables it to self expand quickly and forcefully without the aid of a balloon catheter as well as enables it to securely hold the graft within lumens carrying high volume of blood.
The present delivery catheter includes structure for quickly deploying the graft within the lumen to be repaired. Further, by not employing a balloon catheter, the delivery catheter may be utilized to repair lumens located near the heart without placing undue stress on the heart and is configured for packing a larger diameter graft within the delivery catheter. Additionally, the delivery catheter is configured to hold the attachment systems affixed to the ends of the graft within capsules and by not placing the entire graft within a single capsule, larger diameter grafts may be packed within the delivery catheter. Moreover, the delivery catheter is longer which enables it to reach an aortic arch and employs a novel releasing system cooperating with the capsules which, in conjunction, operate to facilitate loading as well as deployment of the graft. The releasing system includes a release wire cooperating with releasable ties attached to the exterior of the graft to maintain the attachment systems of the graft in a collapsed configuration and to facilitate the expansion of the attachment systems so that they properly and quickly engage the walls of the lumen.
The present invention provides a prosthesis or graft for intraluminal placement in a fluid conducting corporeal lumen. The graft is hollow and has a pre-selected cross-section, length and wall thickness. The graft is deformable to conform substantially to the interior surface of the corporeal lumen or other body part to be repaired. The midsection of the graft may be crimped to resist kinking and facilitate placement accuracy and may comprise radiopaque markers attached along its length to help orient the graft using fluoroscopy or X-ray techniques. Tufts of yarn are sewn into the graft at its ends to facilitate healing and placement of the graft within the corporeal lumen. Preferably, the graft comprises woven polyester or another material suitable for permanent placement in the body such as PTFE. The superior and inferior ends of the graft are positioned within the corporeal lumen and the graft is configured such that it traverses the diseased or damaged portion of the vessel. To anchor the graft to the wall of the corporeal lumen, attachment systems are secured to the superior and inferior ends of the graft.
The preferred attachment system includes wall engaging members. The wall engaging members of the superior attachment systems are angled toward the inferior end of the graft. Similarly, the wall engaging members of the inferior attachment systems are angled toward the superior end of the graft. Specifically, the angles of both the superior and inferior wall engaging members are in the range of 60-80xc2x0 from radial. The wall engaging members of both attachment systems have sharp tips for engaging the corporeal lumen wall. The preferred attachment systems are formed into a staggered V-shape lattice or framework, the apices of which comprise helical torsion springs. The frame of the attachment systems allows for elastic radial deformation resulting in a spring-like effect when a compressed attachment system is allowed to expand as the graft is released from the capsules, and by having a high stiffness, they function to quickly and forcefully seat the graft within the lumen.
Preferably, the delivery catheter of the present inventor is flexible and includes an elongate cylindrical jacket overlaying a superior capsule assembly and an inferior capsule assembly, each of which are adapted to releasably retain an end of the graft. The superior capsule assembly further includes an elongated flexible conical-shaped or tapered nose cone adapted to facilitate the advancement of the delivery catheter through a patient""s vasculature. Attached at the most proximal end of the inferior capsule assembly is an elongate outer shaft, comprising an inferior capsule catheter, which is adapted to receive a multi-lumen-inner shaft. The lumens of the inner shaft are conduits for a guidewire, one or two release wires, an anti-elongation wire and a control wire that cooperates with the superior capsule assembly. Attached to the inner shaft and distal to the outer shaft/inferior capsule assembly junction is a conical-shaped knob that cooperates with the superior capsule assembly. Also attached to the inner shaft is an anti-elongation wire that functions to minimize elongation of the inner shaft during deployment of the graft. The jacket is capable of moving relative to the rest of the catheter and thus can be withdrawn, thereby exposing the capsules and graft. Similarly, the capsules can be caused to move relative to the inner shaft and the structure attached thereto, which, in conjunction with the operation of the releasing system, thereby causes the deployment of the graft within a lumen. The length of the delivery catheter is sufficient for use in reaching the thoracic portion of the aorta and has a diameter suited for encasing a graft for use in repairing a thoracic aneurysm.
Deployment of the graft comprises a series of steps which begins with introducing the delivery catheter into the corporeal lumen using well known surgical techniques. The delivery catheter is manipulated so that the graft retained by the superior and inferior capsule assemblies is positioned at a desired location within the corporeal lumen. Once the graft is in the desired location, the jacket is retracted and the superior and inferior capsule assemblies are removed from the graft to expose the superior and inferior attachment systems of the graft. After this is accomplished, the releasing system is employed to thereby allow the attachment systems self-expand and seat the graft within the lumen.
Two methods are contemplated for placing the graft within a lumen. As a first step in each method, the jacket is moved proximally to expose the graft retained by the superior and inferior capsules. In the first method, the superior capsule assembly is moved distally to expose the superior end of the graft and the inferior capsule assembly is moved proximally to expose the inferior end of the graft. The releasing system is then employed to release the superior attachment system, thereby allowing the superior attachment system to affix the superior end of the graft within the lumen. Thereafter, the releasing system is employed to release the inferior attachment system to thereby allow the inferior attachment system to affix the inferior end of the graft within the lumen. In the second method, these steps are reordered so that the inferior end of the graft is first seated within the lumen and thereafter, the superior end is seated.
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanied drawings, which illustrate, by way of example, the features of the invention.